Compound plant for producing mechanical power and heating steam with gas and steam turbines



A. HERMITTE EI'AL 2,633,707 COMPOUND PLANT FOR PRODUCING MECHANICAL POWER AND HEATING WITH GAS AND STEAM TURBINES April 7, 1953 Filed Nov. 15, 1947 2 Sl-lEETS--SHEET l 9 10 F 2' 15 6 2 A Q 6 1 1 is i is 15 1z 06 g.

m K OK i4 12 Inventors Louis A- Herrnifle Marcel H.111 Sd-Llle A Hornegs Apr!1 7, 1953 A. HERMITTE EI'AL 2,633,707

COMPOUND PLANT FOR PRODUCING MECHANICAL POWER AND HEATING WITH GAS AND STEAM TURBINES Filed Nov. 13, 1947 2 SHEETSSHEET 2 Fig. 2

Louis A.Herrn1'iie Marcel H.L-S &-i.ue

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Patented Apr. 7, i953 ooMPoUND PLANT FOR- PRODUCING ME- 7 CHANICAL POWER AND HEATING STEAM WITH GAS AND STEAM TURBINES Louis A. Hermitte and Marcel H. L. Sdille, Paris. France, assignors t'o Societe Rateau (Societe Anonyme), Paris,.France, a company of France,

and Rene Anxio'nnaz, Paris, France, jointly Application'November 13, 1947, Serial No. 785,778

In France December 16,1946;

1 Claim. 1 (or 60-49) It is a known-fact that in compound plantsnsed for producing simultaneously heating steam and mechanical power, the amount of energy recovered for a predetermined amount of heating units is all the greater when the maximum temperature to be used in the corresponding cycle is higher.

- From this standpoint gas turbines which are already now capable of operating at temperatures that are higher than steam turbines show obvious advantages.

cycle during the expansion stage.

The following description and accompanying drawings given out by way of example and by no means in a limitative sense, will allow understanding how the difierent embodiments of the invention may be executed, the features appearing either in the drawing or in the specification forming obviously part of said invention. In said drawings:

Figs. 1 and 2"illustrate respectivelythe cycle according to the invention and the'corresp'on'ding simplest diagram 'of'a compound plant for the production of energyand heating steam." j

Figs. 3 and 4 illustrate also the cycle and'the diagram of a compound plant for producing energy and heating steam with the addition of means of heating during expansion and for cooling during compression inside the driving unit incorporating the gas turbines.

Lastly, Fig. 5 illustrates the application of the invention to a compound plant incorporating a driving u t with gas turbines of th semi-open tr ig. 1 is an entropic diagram giving absolute temperatures versus entropy for illustrating the stages affecting the gases and the steam. It is assumed by way of simplification that the expansions and compression are performed adiabatically. The conventional cycle of the gas turbine includes an adiabatic compression |2, a heating stage under constant pressure 2-3-4, an adiabatic expansion 45 and a cooling stage under constant pressure conditions 5--6-'|l. For the steam turbine, the water is delivered to the feed pump in accordance with line l5- -9. It is then vaporized and superheated under constant pressure conditions as shownat 9 40-4 I and then expands adiabatically while providingenergy at ll- -l2 andfinally abandons its heat to the utilisation circuit at l28--I5. When the feed water is heated through tappings executed during expansion, the evolution of the steam is equivalent to that shown by the cycle 89-l0- ii--l28 wherein the condensation is stopped at point 8. Under such conditions, the exhaust gases from the gas turbinethat the water in a heat-recovering boiler may--theoretically pass out of the latter at the temperature of saturation of the steam at 6; Fromtto-l. thepresent invention provides for the use of the heat remaining in the exhaust gases in order-to heat the air of the gas cycle after compression and before combustion in the first combustion chamber. The use of this remainin heat is all the more considerable when the steam from the auxiliary cycle is produced at a higher temperature and the compressed air'is at a lower temperature. It is thus always of interest to'cool the air of the gas cycle during compression if the rate of compression reaches a high value. The hatched surface of the diagram illustrates the amount of heat given up by the steam and abandoned thereby for utilisation purposes.

Fig. 2 shows'by way of example a form of execution of the compound cycle that has just been described. The engine including a gas turbine is constituted in its simplest form by an air compressor C driven by the gas turbine T that on the other hand produces useful power and; for instance, drives an electric generator RI. The exhaust gases from the gas turbine feed a boiler Chi producing the steam of the steam cycle and then a heat exchanger El providing a first heating of the air delivered by the compressor C, the su s qu nt h ting of the a r ior dr ving the turbine T being performed in the combustion chain ber ChZ. The associated steam cycle includes also a counter pressure turbine Top driving an electric enerator R2. The exhaust from said turbine Tcp feeds the heating circuit U delivering to the outside of the plant the desired heat. The heating of the feed water delivered to the boiler Chl by the pump pl and obtained through the condensation of the heating steam may be performed through the heat exchangers el-e2 fed by tappings of steam from the expansion side of the turbine Top ahead of the heating circuit U. Furthermore it is possible to limit the amount of heat fed to the heating circuit U by providing a second air heating device E2 that uses a fraction of the flow of exhaust gases directly from the turbine T, the air compressed by the compressor flowing then in succession through the heat exchangers El-E2 before entering the combustion chamber-C712 in accordance with the dotted line showing. the travel thatv the air is constrained to follow upon closing of the valve 1).

The compound cycle described hereinabove may be still further improved to a substantial extent by cooling on one hand the air duringits compression and on the other hand by executing the expansion of the driving gases in several turbine stages separated by intermediary heating means for said gases. The entropic dia ram is then transformed into that illustrated in Fig. 3; it difiers from that of Fig. 2, by the line I, 2', l, 2 corresponding to two successive steps of compression I, 2' and I, 2 with'an' intermediary cooling from 2 to I and by the line 4, 4', 5 corresponding to two successive steps of expansion 4, 5 and 4', 5 with an intermediary heating from 5 to 4'. The apparatuses are grouped in such a case as shown diagrammatically in Fig. 4,. It differs from that of Fig. 2 through the incorporation of two. gas turbines in series Trip and Tspwith an intermediately combustion chamber CM and of two bodies for the air compressor .CBP and Car in series with the interposition of an air cooler r.

In the arrangement described above and in other i la ar an eme s. whi h m y e adopted care must be taken to determine the various parts so that the temperature of the gases at the output from the boiler may be higher than the temperature of the air at the end of the compressionin the cycle of the gas turbine.

Fig. 5 illustrates such an application corre-. sponding to a compound plant for producing mechanical power and heatingsteam. The arrangement is very similar-tothat of Fig. 2 but it includes in addition thereto an auxiliary gas unit To, Co and R0, the compressor 00 of which delivers the required amount of combustive air into the closed circuit of the principal gas group T, C, R and of which the turbine To uses the available expansion betweenthe exhaust of the main turbine and room atmosphere. The boiler for producing steam at Chi and the principal heat exchanger E and also an air cooler r are then inserted in the circuit between the. turbine and the combustion chamber of the principal group ahead of the suction of'the main compressor C.

What we claim is:

In a compound plant for simultaneously pro:

ducing mechanical power and steam available for heating purposes comprising a fuel burner, an air compressor for delivering compressed air to said burne nto support combustion, a gas turbine. arranged to receive combustion gas from said burner as a motive fluid, said turbine being coupled with said compressor for driving the same, a steam producer comprising a passage wherein combustion gas from said burner is passed in indirect heat exchange relationship with water to'be vaporized, a power steam line connected with said steam producer to be supplied with steam therefrom, said line being separate from saidgas turbine, and exhaust operated means for heating air on its way from .said compressor to said burner, the combination of 'irst gas conveying means for passing combustion'gas from said burner directly to the inlet side of said turbine in a substantially uncooled condition, second gas conveying means for passing exhaust from said gas turbine directly to and through said passage in said steam producer so as to produce steam at high temperature, third gas conveying means for passing said exhaust from said steam producer to said exhaust operated air heating means, means for withdrawing a portion of exhaust from the second-named gas conveying means and leading the same to the third-named gas conveying means in by-pass to said steam producer, and means for withdrawing a portion of air on its way from said exhaust operated air heating means to said burner, passing the same in indirect heat exchange relationship with said portion of exhaust thus by-passed, and mixing it again upstream with respect to said burner with the remainder of air from which it was withdrawn. 7

" LOUIS A. MARC EL H. L. SEDILLE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number 2,423,136 arr Sept. 30', 1947 

